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BigCalm : AIX UNIX : Handy AIX Commands

AIX COMMAND GUIDE


Making files is easy under the UNIX operating system. Therefore, users tend to create numerous files using large amounts of file space. It has been said that the only standard thing about all UNIX systems is the message-of-the-day telling users to clean up their files. -- System V.2 administrator's guide


Quick Alphabetic Look-Up


Basic File Handling Inputs, Outputs and Wildcards Other File Handling Commands Extremely Useful Commands
General Information Commands System Commands Connectivity Tapes and Disks
Screen Communication Source Code Control System (SCCS) Miscellaneous Shell Scripts



INTRODUCTION

This is my unix command help file which has been built up over the years. This file was built primarily for my own reference and is not intended to be an authoratative guide to all commands for AIX - often if there is a very short description for a command, you can take this as RTFM. I am not a systems administrator, but have been called on to do the job occasionally (and install a box or two) - this helpfile should be ideal for people who use AIX, but aren't responsible for the deep magic required for hardware configuration.

You may find this file helpful despite the numerous omissions nonetheless. This file was originally a plain text file but I have converted to HTML using Lemmy (A vi clone for Windows).

Because it has been hand-converted from the original text document, there's a few hangovers from it that I just can't be bothered to remove such as the caps headings. Additionally, some browsers may not render certain characters.

I've tried (and quite probably failed) to keep several conventions within this document - any command, if mentioned in the description of another command should have a bookmark link to the description of that command; all examples are in blue text - apologies to lynx users, but examples should be written so that they're recognisable anyway (and if you're using lynx, you probably know unix quite well anyway so I don't really know why I'm apologising ;-). If a command has more than one useful option, I've tried to put them into <UL> Unordered list tags.

If a command stands almost alone, or is complex within itself, it doesn't appear in this file but in it's own separate file (with a link if I've converted it to html. Examples are vi and awk.



BASIC FILE HANDLING

ls
- list files in directory; use with options
For a more detailed description of ls see ls -l

more
- used to control input by pages - like the dos /p argument with dir. e.g.
$ more /etc/motd *******************************************************************************
* *
* *
* Welcome to AIX Version 4.1! *
* *
* *
* Please see the README file in /usr/lpp/bos for information pertinent to *
* this release of the AIX Operating System. *
* *
* *
*******************************************************************************
motd: END

Useful keys for use with more: See also pg which is extremely similar

pg
- used to control input by pages - like the dos /p argument. pg performs the same function as the more command but has different control, as it is based on ex
Helpful keys for pg:

pwd
- show present working directory. e.g.
$ pwd
/usr/live/data/epx/vss2

To change the current working directory use cd

cd
- change directory (without arguments, this is the same as $ cd $HOME or $ cd ~)

cp
<source> <destination> - copies a file from one location to another. e.g.
$ cp /etc/hosts /etc/hosts.backup # make a backup of the hosts file
$ cp /etc/motd /tmp/jon/ # Copy file /etc/motd to directory /tmp/jon/

Options synonym: copy

mv
<source> <destination> - move a file from one location to another. e.g.
$ mv /tmp/jon/handycommands.txt . # move handycommands in /tmp/jon to current directory
$ mv -f vihelp vihelp.txt # Move file vihelp to vihelp.txt (forced)

Options synonym: move
.

rm
<filename> - removes a file. e.g.
$ rm /tmp/jon/*.unl # remove all *.unl files in /tmp/jon
$ rm -r /tmp/jon/usr # remove all files recursively
Options

du
Recursively lists directories and their sizes. e.g.
$ du /etc # list recursively all directories off /etc
712 /etc/objrepos
64 /etc/security/audit
536 /etc/security
104 /etc/uucp
8 /etc/vg
232 /etc/lpp/diagnostics/data
240 /etc/lpp/diagnostics
248 /etc/lpp
16 /etc/aliasesDB
16 /etc/acct
8 /etc/ncs
8 /etc/sm
8 /etc/sm.bak
4384 /etc
The sizes displayed are in 512K blocks. To view this in 1024K blocks use the option -k

lp -d<Printername> <Filename>
send file to printer. e.g. $ lp -dhplas14 /etc/motd # send file /etc/motd to printer hplas14
$ lp /etc/motd # send file /etc/motd to default printer

cat
- print a file to stdout (screen). e.g.
$ cat /etc/motd # display file /etc/motd to screen
*******************************************************************************
* *
* *
* Welcome to AIX Version 4.1! *
* *
* *
* Please see the README file in /usr/lpp/bos for information pertinent to *
* this release of the AIX Operating System. *
* *
* *
*******************************************************************************
cat is also useful for concatenating several files. e.g.
$ cat fontfile IN* > newfile # appends fontfile and all files beginning with IN to newfile
Though this might seem an essentially useless command, because most unix commands always take a filename argument, it does in fact come in extremely useful at more advanced levels. Awards are given out occasionally for the most useless usage of cat. If an option of '-' is specified, cat will take its input from stdin.

INPUTS, OUTPUTS AND WILDCARDS


Unix commands generally get their information from the screen, and output to it. There are three main 'streams' which unix uses to get/place it's information on. These streams are called:
any of these may be redirected by the following symbols:
command1 & - the ampersand (&) forces command1 to run in the background. so that you may continue to type other commands in the shell, while command1 executes. It is not advisable to run a command in the background if it outputs to the screen, or takes it's input from the screen

See also tee which allows splitting of the input stream and output to several different places at once.

Wildcards

B Bib Baby Fox Fib

There are various wildcards which you may use. One is '*' which means 0 or more characters. e.g. 'B*' will match 'B,Bib and Baby' from the list above, another wildcard is '?' which matches 1 character, e.g. '?ib' will match 'Bib and Fib'. Wildcards differ depending on the program in use: awk derivatives (awk,sed,grep,ex,vi,expr and others) have the following special characters: Given the following four lines:

Chargeable calls in bundle: $47.50
Chargeable calls out of bundle: $20.50
Other bundle charges: $0.00
Total Charge: $20.50

$ grep "^Charg.*bundle.*\$.*"
would match the first two lines.
In english - match all lines which start with 'Charg', then have any number of characters and then the word 'bundle', then have any number of characters, and then a dollar symbol, and then have any number of characters following to the end of the line

OTHER FILE HANDLING COMMANDS


type <command>
- show where the source of a command is: e.g.
$ type sendmail
sendmail is /usr/sbin/sendmail

This command is merely an alias for 'whence -v'

whence <command>
- show where the source of a command is: shell builtin command. See type
Use option: -v for verbose mode

which <command>
- show where the source of a command is held. Almost the same as type and whence

chmod <Octal Permissions> <file(s)>
- change file permissions. e.g.
$ chmod 666 handycommands
changes the permissions (seen by ls -l) of the file handycommands to -rw-rw-rw-
r = 4, w = 2, x = 1. In the above example if we wanted read and write permission for a particular file then we would use r + w = 6. If we then wanted to have the file have read-write permissions for User, Group and All, then we would have permissions of 666. Therefore the command to change is that above.
$ chmod 711 a.out
Changes permissions to: -rwx--x--x
Additional explanation of file permissions and user/group/all meaning are given in the description of ls -l
You may specify chmod differently - by expressing it in terms of + and - variables. For example
$ chmod u+s /usr/bin/su
will modify the "sticky bit" on su, which allows it to gain the same access on the file as the owner of it. What it means is "add s permission to user". So a file that started off with permissions of "-rwxr-xr-x" will change to "rwsr-xr-x" when the above command is executed. You may use "u" for owner permissions, "g" for group permissions and "a" for all.

chown <Login Name> <file(s)>
- Change ownership of a file. Must be done as root. e.g.
chown informix *.dat # change all files ending .dat to be owned by informix

chgrp <Group Name> <file(s)>
- Change group ownership of a file. Must be done as root. e.g.
chgrp sys /.netrc # change file /.netrc to be owned by the group sys

mvdir <Source Directory> <Destination Directory>
- move a directory - can only be done within a volume group. To move a directory between volume groups you need to use mv -r
or find <dirname> -print | cpio -pdumv <dirname2>; rm -r <dirname>

cpdir <Source Directory> <Destination Directory>
- copy a directory. See mvdir

rmdir <Directory>
- this is crap - use rm -r instead

mkdir <Directory>
- Creates a directory. e.g.
$ mkdir /tmp/jon/ # create directory called /tmp/jon/

find <pathname> -name "searchkey" -print
- search for files - e.g.
$ find . -name "system.log" -print # will find all files (with full path names) called system.log - Wildcards are allowed, e.g.
$ find /tmp -name "sl.*" -atime +0 -print # will print out all files in /tmp/ that start sl. and which haven't been accessed for a day. Helpful for finding lost files, or finding stuff in enormous directories. Other useful options include:

ln -s <Directory> <symbolic link>
- create a symbolic link to a different directory from current directory: e.g.
$ ln -s /usr/uniplex/compgnc /u/compgnc/uni # would create a link called 'uni' in the directory /u/compgnc. From then on, typing cd uni would cd to /usr/uniplex/compgnc. You can also give two files the same name. e.g.
$ ln make.e_enquiry makefile # would link the two files so that they are identical, and when you change one, you change the other. You may also create a symbolic link to a host(!). Instead of typing 'rlogin hpserver' every time, by typing
$ ln -s /usr/bin/rsh hpserver # will create a link so that whenever you type 'hpserver' it will execute a remote shell on the machine.
Option -f forces the link to occur

head -<Number> <FileName>
- prints out the first few line of a file to screen. Specify number to indicate how many lines (default is 10). e.g. If you sent something to a labels printer and it wasn't lined up, then you could print the first few labels again using:
$ head -45 label1.out | lp -dlocal1

tail -<Number> <FileName>
- prints out the end of a file. Very similar to head but with a very useful option '-f' which allows you to follow the end of a file as it is being created.e.g.
$ tail -f vlink.log # follow end of vlink.log file as it is created.

wc -<options> <FileName>
- Word Count (wc) program. Counts the number of chars, words, and lines in a file or in a pipe. Options: To find out how many files there are in a directory do ls | wc -l

split -<split> <FileName>
- Splits a file into several files.e.g.
$ split -5000 CALLS1 # will split file CALLS1 into smaller files of 5000 lines each called xaa, xab, xac, etc.

tr <character> <other character>
- translates characters. e.g.
$ cat handycommands | tr "\t" " " # will take the file handycommands and translate all tabs into spaces. Useful when messing about with awk or you need to convert some input (e.g. that from tty) to a unique filename that does not contain special characters. e.g.
$ tty | tr "/" "." # produces for example .dev.pts.7

od <options> <filename>
- od converts nasty (binary save) files into character representations. Useful when back-compiling, examining raw .dat files,etc. Use with option '-c' for character display (recommended).

script
- starts recording everything in the shell to a file by default 'typescript'. Press ^D to finish the script. Provides a log of everything used. Has almost the same effect as $ ksh | tee typescript
Used for debugging shells, seeing error messages which flash off the screen too quickly, etc.

cut
- cut's the file or pipe into various fields. e.g.
$ cut -d "|" -f1,2,3 active.unl # will take the file active.unl which is delimited by pipe symbols and print the first 3 fields options:
Not too useful as you can't specify the delimiter as merely white space (defaults to tab) Alternatively, you can 'cut' up files by character positioning (useful with a fixed width file). e.g.
$ cut -c8-28 "barcode.txt" # would cut columns 8 to 28 out of the barcode.txt file.

paste
- paste will join two files together horizontally rather than just tacking one on to the end of the other. e.g. If you had one file with two lines:
Name:
Employee Number:
and another file with the lines:
Fred Bloggs
E666
then by doing:
$ paste file1 file2 > file3 # this would then produce (in file3).
Name: Fred Bloggs
Employee Number: E666
Note that paste puts horizontal tabs between the files, so you may need a sed 's/   //g' command to get rid of these.

sort <filename>
- sorts the information from the file and displays the result on standard output (stdout). e.g.
$ sort /tmp/list_of_names # will sort the file into alphabetical order, and display it to the screen. Useful with option '-u' to filter out duplicates.

uniq <filename>
- filters out all duplicate lines from a file or input stream (file or stream must be sorted!). Useful with option -c which merely produces a count of unique lines.

ex <filename>
- ex is an old line editor, and almost never used now (similar to DOS edlin if you remember that - me, I've repressed it). You are most likely to come across ex within the vi editor - all commands beginning with a colon (:) are ex commands

EXTREMELY USEFUL COMMANDS

ls -l
- lists files in a directory in long format. You cannot do without this. Here's a more detailed explanation. e.g.
$ ls -l
Part 1Part 2Part 3Part 4Part 5Part 6Part 7
-rw-rw-rw-1rootstaff28Jan 16 09:52README
-rw-------1compjmdstaff4304Jun 24 12:21tabledict
drwxrwxrwx2compjmdstaff512Jul 1 16:30testdir
-rwxrwx---1compjmdsystem0Jul 1 16:30a.out

... is a sample listing.

Useful options (and there are loads more). All may be combined except where specified:

vi <filename>
- love it or loathe it - the standard operating system text-file editor. See Related help file. Vi You can also use 'view' which forces Read only (-R opt). vi +<number> enters the file at the specified line no. Also, vi +/<Search pattern> will enter the file and move to the first occurrence of <Search pattern>. e.g.
$ vi +/"love it or loathe it" handycommands
Users new to vi hate it. I personally managed to get through University without using it ever (I used Joe's own editor instead). If I accidentally went into vi, I had to ^Z and kill the job. Sigh. Five years of using vi means that I'm getting a little better at it now... (I'm actually typing this now in a vi-clone for Windows).

grep <pattern> <file(s)>
- a phenomenally useful command which matches strings within files - e.g.
$ grep D7523 mcall_reps.out # will find all the lines in mcall_reps.out that have the string "D7523" in it. Also incredibly useful for things like pipes,e.g.
$ du | grep cred # (in /home directory will show all users that have 'cred' in their title). You may use regular expression matching - e.g.
$ grep "main.*{" x.c # would match any line containing 'main' and an open curly brackets at any point in the line afterwards. There are two variations to grep - fgrep and egrep which do virtually the same things as grep, but are either faster (having less options) or more complex (but slower). See also section on Wildcards
Options:

ksh -o vi
- The Korn Shell - pros might notice that I don't mention using the C-Shell at all - I've never used it, so that's why it doesn't appear. A Shell is a program that you run your commands in. Typing exit will end the current shell. The -o vi option of the korn shell allows vi commands to work at the shell prompt after pressing escape. For example, pressing escape and then 'k' will bring up the last command used in the shell.

awk
- this would be a damn useful command if I knew how to use it properly. see alternative page awkhelp

man <command>
- look at the manual, e.g.
$ man ps # will list the manual page for the command ps

GENERAL INFORMATION COMMANDS

smon
- monitor's system usage - F5 shows processes which are hogging the machine. Not available on AIX 4.1 and above sadly.

uptime
- shows how long the system has been up and how hard it is being hammered. The load average fields show how many jobs on average are waiting. <1 or less is very good, around 5 is pretty bad (though not unusual), >10 the machine is being seriously hammered.

who
- list users who are currently logged on (useful with option 'am i' - i.e. 'who am i' or 'whoami')

w
- list users and what they are doing, including idle time. The first line is the output from uptime

id
- similar to whoami except that it does a direct check to see who you are - who only checks /etc/utmp so any su commands will be ignored.

ps
- list processes currently running, by default on the current shell. Useful with options:

fuser -u <filename>
- show who is using a file.(system hogging command). Useful when trying to work out who has locked a row or table in an informix database for example.

lpstat -p <printer>
- show the current status of a printer and any jobs in the queue. lpstat without arguments prints all of them.

enable <printer>
- enable a printer queue. You must be root or a member of the printq group to run this command.

disable <printer>
- disable a printer queue. You must be root or a member of the printq group to run this command.

enq <various parameters>
- examine spool queue for printers.

uname -a
- will show you what machine you're currently on.

ipcs
- list semaphores and shared memory.

ipcrm -s <semaphorenumber>
- remove semaphore or shared memory.

crontab
- use -l to list all regular scheduled jobs. To alter them, use option -e

at <now + ?? seconds/minutes/hours/days/years>
- perform a job at a specified time. (Useful for running something at a later date). at retains the current environment. e.g.
$ at now + 5 minutes
echo "Phone Julie McNally" > /dev/tty616
^D
job compjmd.389748732 will be run at ???
Will echo to tty616 the message "Phone Julie McNally" in 5 minutes. e.g.2
$ at 0331235930
echo "April fools day!" > /dev/console
^D
will echo "April fools day!" to the console at 11:59 and 30 seconds, on the 31st of march. Format for this is: [YYYY]MMDDhhmmss. at jobs are sometimes used in the place of crontab's because if the machine is off when the crontab is meant to take place, the job never happens. at jobs automatically start when the machine is switched on if the machine was down at the time. typing at -l will show you all the at jobs you have queued, at -r <atjob> will remove an at job (only the owner or root is allowed to do this).

date
- show current date and time. This command may also be used to set the system clock (ONLY WHEN EVERYONE IS LOGGED OFF) with a root user id. A date change is never simple, even when adjusting things by an hour. The safest way to do it is to change the date then reboot the machine because otherwise the crontab daemon may start doing jobs at odd times. I believe there might be a 'go slow/fast' option to set the clock, and the clock will then run 'slower/quicker' until it catches up with the required time.

last <username>
- shows a list of recent logins. It looks at /var/adm/wtmp so it only shows initial logins, and not whether those users have been su'd to.

fileplace -pv <filename>
- show the physical (as in disk location) location of a file. Useful for tracing informix files, and perhaps for working out whether defragmentation copying is required.

SYSTEM COMMANDS

kill -<Signal> <process>
- sends a signal (normally a kill) to a process. kill -9 terminates the job no questions asked, kill -15 tries to clear up as much as possible - e.g. remove semaphores and such-like. Other signals may be sent as well, see manual and /usr/include/sys/signal.h to see what signals you can send to a process.

renice <priority> <process>
- make a process not hog the system so much by setting its nice value.

smit
- system admin program for AIX

df
- list volume groups + usage. see also lsvg. Usually used with the -k flag so the number of blocks is displayed in 1024-blocks.

cu -l <device>
- log on to device such as a pad or a modem. See related files /etc/uucp/* and /etc/locks and /etc/services

stty sane
- Changes terminal settings back to normal. If a tetra module for example crashes your screen so that no keys function except ^C which doesn't even do very much then typing ^Jstty sane^J should cure the problem. To fully cure the problem you also need to type stty tab3 (and stty -ixon if you're feeling a little overzealous)

stty
- allows you to change terminal settings such as the interrupt key, quit key, etc. e.g.
$ stty intr ^A # would change the interrupt key to being control-A
$ stty quit ^L #would set the quit key (normally ^\) to control-L. other key changes are: To really annoy a systems administrator, change interrupt to 't' and quit to '^D' . hehehehehehe

lscfg
- show all connected devices

lsvg
- list volume groups (see related file diskhelp)

lspv
- list physical disks (and see related file diskhelp)
lspv without arguments will produce a list of all the hard-disks used. lspv <hard-disk-name> will produce a list of information about the hard disk. lspv -l <hard-disk-name> will show any logical volumes which are mapped on to that drive.

lsdev
- list devices. Options: produces different output when you are root.

mkdev
- make devices. e.g. To make a tty:
# Script to add a tty. Options that need amending are:
# -l name of tty to be created - e.g '-l tty600' wil create
# a tty called 'tty600'
# -p RAN name
# -w Port number on RAN
# -a Attributes (e.g. to set up auto login, etc.)
mkdev -c tty -t 'tty' -s 'rs232' -l tty433 -p sa2 -w 2 -a term='wyse50' -a forcedcd='enable' -a login='enable' -a speed='19200'
e.g. To create a printer (raw device):
mkdev -c printer -t 'osp' -s 'rs232' -p 'sa3' -w '10' -l label2 -a xon='yes' -a dtr='no' -a col=500
It is highly recommended that you make and change devices using smit

chdev
- change devices. See mkdev

cc
- c compiler, use with

shutdown
- shutdown the system so that it may be switched off. Rather obviously, this may only be run by root. Options:

oslevel
- show the current revision of the operating system.

CONNECTIVITY

exit
- end current shell process. If you log in, then type this command, it will return you to login. ^D (control-D) and logout (in some shells) does the same.

rlogin
- login to a remote machine, e.g.
$ rlogin hollandrs # log in to machine called hollandrs
Useful with -l option to specify username - e.g.
$ rlogin cityrs -l ismsdev # log in to machine cityrs as user ismsdev For further info about trust network see .rhosts file and /etc/resolv.conf (I think).

telnet
- very similar to rlogin except that it is more flexible (just type telnet with no arguments and then '?' to see the options). Useful because you can specify a telnet to a different port.

ftp
- File Transfer Protocol - a quick and easy method for transferring files between machines. The .netrc file in your $HOME directory holds initial commands. type ftp without arguments and then '?' to see options)

rcp
- Remote copy. Copies a file from one unix box to another, as long as they trust each other (see .rhosts file or /etc/resolv.conf I think). Options

su - <loginname>
- switch user, option '-' means that the users .profile is run, without option you merely assume the id and permissions of the user, without (for example) changing PATH and DBPATH, e.g.
$ su - root # become root
$ su root # gain permissions of root but don't change the current environment variables
$ su - vlink # switch to user vlink
If you are root, you may su to any other user without being prompted for a password. su without arguments is the same as 'su root'. Note that the 'su' option is not available on all UNIX machines as it can crash some of them.

ping <hostname>
- check that <hostname> is alive and well (do not expect an immediate response from a machine that is linked over an ISDN line). Firewalls often block ping packets after the Ping of Death so quite often you'll find you can't ping internet sites either. Options include: To check that your machine can ping, try pinging 127.0.0.1 - this acts as a feedback loop, checking the network card's ability to ping.

rsh <hostname> <commands>
- remote shell - e.g.
$ rsh altos more /tmp/chk # will run the command more the file /tmp/chk on the machine called altos. Useful in pipes for example. rsh on its own will execute a login. Use option '-l' to specify logon name. You can also use rcmd and remsh on other flavours of unix.

host <ip address>
- lookup the ip address in the /etc/hosts file and give its name

TAPES AND DISKS

Please see this page for more information on disks in AIX

dd if=<filename or device> of=<filename or device> bs=<Block Size> conv=sync
- direct (and I mean DIRECT) copy, normally to tape. Archaic syntax and very rarely used. flags:
e.g. To write a file to tape use
$ dd if=/etc/hosts of=/dev/rmt0 bs=1024 conv=sync # write hosts file to tape using dd

cpio
stands for copy in-out, and is extremely powerful if you can cope with the innumerable flags that you have to use(!)
$ cpio -iBcvumd "etc/hosts" </dev/rmt0 # Grab /etc/hosts file from tape
$ find /etc -print | cpio -oBcv >/dev/rmt0 # Write the contents of the /etc directory to tape
$ find /etc -print | cpio -pdumv /usr2/etcbackup/ # copy directory /etc to /usr2/etcbackup and retain all permissions.
meaning of the flags:

tapeutil -f <devicename> <commands>
- A program which came with the tape library to control it's working. Called without arguments gives a menu. Is useful for doing things like moving tapes from the slot to the drive. e.g.
$ tapeutil -f /dev/smc0 move -s 10 -d 23 # which moves the tape in slot 10 to the drive (obviously, this will depend on your own individual tape library, may I suggest the manual?).

doswrite -a <unix file> <dos file>
- copy unixfile to rs6000's floppy disk drive in DOS format. -a option expands certain characters, for certain ascii conversions.

dosdir <directory>
- show list of files on a dos floppy disk. Useful with option -l (long format). Like dos command 'dir'

dosread -a <DOS file> <unix file>
- copy dos file in floppy disk drive to unix - if UNIXFILE is omitted, it outputs to the screen.

dosdel <DOS file>
- delete dos file on floppy disk.

dosformat
- format dos floppy disk (High Density)

tar
- Read/Write stuff to archive.
tar cvf /dev/rmt0 <filenames> # will write files to tape
tar xvf /dev/rmt0 will read files from tape
tar tvf /dev/rmt0 will give a listing of what's on the tape. If you're using an archive file then replace /dev/rmt0 in the examples above with the name of the archive file.

SCREEN COMMUNICATION

echo
- a command mainly used in shell scripts. Examples:
$ echo "Hello" # will print Hello on your screen
$ echo "Hello" > /dev/tty616 # will print Hello on someone elses screen (warning - can crash their screen!)
$ echo $DESTF10 # will print the value of the environment variable DESTF10
$ echo "\033Fdemo demo" # will echo demo to the status bar at the top of a wyse terminal
See also file shellscripts

read
- will read text from standard input and place it in the variable name specified. See file shellscripts

line
- waits until the user presses return before carrying on (writes what is typed to standard output). If used in a crontab/at job this instruction is ignored. See file shellscripts

talk <user>
- set up an interactive communication dialogue box between two users. Looks good but isn't really that useful.

write <user>
- writes a message to someone elses screen. Try typing 'write root' and then type a message, finishing with control-D.

banner <message>
- writes <message> in huge letters across your screen! (max: 10 chars per word)

wall <message>
- send a message to all people on a system. Can only be executed by root (I think).

tput <argument>
- tty type independent attribute setting (requires TERM variable and TERMCAP to be set). I only know these few bits:

tee (-a) <filename>
- command used in pipes to take a copy of the standard output. e.g.
$ ls | tee /tmp/x # would output ls normally and put a copy in /tmp/x. The option '-a' is used to append rather than replace files.

SOURCE CODE CONTROL SYSTEM (SCCS)

SCCS Overview
The source code control system allows versions of a program to be stored in a special file, so that any version may be retrieved. There are a few commands involved (not all of them listed here). All source code files start with 's.'
get -r<revision> <source code file>
- get a program out of source code to read only. Missing out the -r flag gets the most recent version. e.g.
$ get $SCUK/s.parser.c # extracts file parser.c from source code file $SCUK/s.parser.c as read only. See get -e for editing.

get -e <source code file>
- get a piece of code out for edit, so that the code may be modified and a new version created using 'delta'. e.g.
$ get -e $SCUK/s.parser.c # extracts file parser.c from source code file $SCUK/s.parser.c for editing. See get for read-only.

delta <source code file>
- you must be in the directory with the modified piece of code when you execute this command. This adds the latest version to the source code file. e.g.
$ delta $SCUK/s.parser.c # writes file parser.c to the source code file $SCUK/s.parser.c . See get -e for information on how to extract the file from source code.

prs <source code file>
- show comments/details on source code file.

admin -r <revision no> -i <program> <source code file>
- create a new source code file with progam. -r specifies the initial revision of the program and may be missed out (default is 1.1 I think). Must be spaced correctly! admin is also used for sccs administration, but it gets to fear and loathing time pretty fast. e.g.
admin -iparser.c $SCUK/s.parser.c # creates a new source code file called $SCUK/s.parser.c from the file parser.c

unget <source code file>
- cancels a get -e

MISCELLANEOUS

strip <binary compiled file>
- Removes all linking information within a compiled program - basically a way of cutting down the size of an executable.

yes <word>
- yes outputs the word 'yes' as fast as its' little legs can go. Never called on it's own. Always used in pipes. For example:
$ yes | rm *.o # would confirm 'yes' whenever rm prompts for confirmation. You can also use it to output a different word e.g.
$ yes please # would output 'please' to the screen until you kill it (prob. immediately).

SHELL SCRIPT COMMANDS

Are all held on a separate page now. Commands covered are export,if,for, shift, test, while, case, and a few others.


sed '<pattern>'
- used by myself for quick substitutions when tr doesn't seem to be doing its job properly. The syntax of the pattern is similar to vi ex command line. E.g. To substitute all spaces with colon symbols the command is
sed 's/ /:/g' file1 # substitute all occurrences of spaces with colons in file1 and output to stdout.

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28th September 2001 Copyright Jonathan Daniel 2001